Investment Securities - Investment Securities Held to Maturity (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	$ 41,995	[1]	$ 38,920	[1]
Held-to-maturity securities, Unrealized Gains	323		205
Held-to-maturity securities, Unrealized Losses Other-than-Temporary	(1)		(1)
Held-to-maturity securities, Unrealized Losses Other	(353)		(756)
Held-to-maturity securities, Fair Value	41,964		38,368
Mortgage-backed securities Residential [Member] | Agency [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	39,880		35,671
Held-to-maturity securities, Unrealized Gains	302		187
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other	(311)		(665)
Held-to-maturity securities, Fair Value	39,871		35,193
Mortgage-backed securities Residential [Member] | Non-agency Non-prime [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	1		1
Held-to-maturity securities, Unrealized Gains
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	1		1
Collateralized Debt/Loan Obligation Asset-Backed Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost
Held-to-maturity securities, Unrealized Gains	8		9
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	8		9
Asset-backed securities Other [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	14		16
Held-to-maturity securities, Unrealized Gains	4		4
Held-to-maturity securities, Unrealized Losses Other-than-Temporary	(1)		(1)
Held-to-maturity securities, Unrealized Losses Other			(1)
Held-to-maturity securities, Fair Value	17		18
Obligations of foreign governments [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	9		7
Held-to-maturity securities, Unrealized Gains
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	9		7
Other debt securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	99		99
Held-to-maturity securities, Unrealized Gains
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other	(2)		(11)
Held-to-maturity securities, Fair Value	97		88
U.S. Treasury and agencies [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	1,982		3,114
Held-to-maturity securities, Unrealized Gains	8		5
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other	(40)		(79)
Held-to-maturity securities, Fair Value	1,950		3,040
Obligations of state and political subdivisions [Member]
Schedule of Held-to-maturity Securities [Line Items]
Held-to-maturity securities, Amortized Cost	10		12
Held-to-maturity securities, Unrealized Gains	1
Held-to-maturity securities, Unrealized Losses Other-than-Temporary
Held-to-maturity securities, Unrealized Losses Other
Held-to-maturity securities, Fair Value	$ 11		$ 12

[1] Includes only collateral pledged by the Company where counterparties have the right to sell or pledge the collateral.